有机凝胶推进剂兼具有固体和液体推进剂的优点,但其液滴在着火燃烧过程出现了剧烈的膨胀-爆裂及火焰扰动现象,明显不同于常规液体液滴准稳态蒸发燃烧现象,影响了凝胶液体火箭发动机喷雾燃烧流场及其优化设计工作.根据偏二甲肼(UDMH)有机凝胶液滴着火燃烧过程的内部非稳态蒸发特性及其微观分子结构,提出了非稳态多组分蒸发模型、界面追踪多相流蒸发模型、离散元多相流蒸发模型三种有机凝胶液滴液相蒸发模型,重点发展并实现了其中的非稳态多组分蒸发模型,详细分析了后两种多相流蒸发模型所需的技术储备.然后针对静止及对流气相环境下的UDMH有机凝胶液滴,提出了分别采用有限速率化学反应模型、相容性层流火焰面模型解决其气相混合燃烧问题,并详细分析了其中的刚性化学反应源项处理及火焰面方程求解所面临的困难及其解决措施.
The organic gel propellants have the advantages of both solid and liquid propellant,but the catching fire and burning process of organic gel droplet appears obvious vapor ejection and flame disturbance.This unsteady combustion phenomenon of organic gel droplet is different from the quasi-steady combustion of conventional liquid droplet and produces great influence on the spray combustion flow field of gel liquid rocket engine and its optimization design.Based on the unsteady evaporation characteristics inside UDMH(unsymmetrical dimethylhydrazine) organic gel droplet and the micro molecule structure of organic gel propellant,three kinds of liquid phase evaporation model,the unsteady multicomponent evaporation model,the interface tracking multiphase flow evaporation model and the discrete element multiphase flow evaporation model,are proposed.The unsteady multicomponent evaporation model regards the gel droplet as a binary multiconponent droplet,in which the gellant inside the gel droplet is been equivalent to a species with low volatility and high boiling temperature.In order to depict the shape and location variety of vapor bubble inside the gel droplet more precisely,the interface tracking multiphase flow evaporation model regards the gel droplet and the vapor bubble inside it as a single fluid,and uses the Level Set function tracking the interface location of vapor bubble.Based on the micro molecule structure of organic gel propellant,the discrete element multiphase flow evaporation model for the gel droplet regards the gellant and vapor bubble as the aggregation of micro-particles with different properties respectively,and uses the Lagrange method tracking the movement and aggregation of each kind micro-particle.The multicomponent evaporation model has been implemented in our foregoing work,so a summary of the model is presented.And next the main difficulties and the technique preparation about the last two multiphase flow models have been presented and analyzed in detail.In view of mixing and combustion p